Wall surface absorption type moving device and magnet driving method of the wall surface absorption type moving device

ABSTRACT

A wall surface attraction type moving apparatus travels on a magnetic wall surface of a large iron structure for maintenance, inspection and other purposes. The apparatus includes a moving body movable on the wall surface, front and rear wheels, permanent magnets, drive mechanisms each for moving the respective permanent magnet toward and away from the wall surface, permanent magnet position sensors, permanent magnet attraction force sensors, and obstacle sensors. If one obstacle sensor detects an obstacle appearing in the travelling path of the moving body, the corresponding drive mechanism is controlled to retract the permanent magnet which is likely to bump against the obstacle away from the wall surface while the other drive mechanisms advance the other permanent magnets which are unlikely to bump against the obstacle toward the wall surface so that the attraction force of the advanced permanent magnets are increased to supplement the reduced attraction force of the retracted permanent magnet. With this arrangement, the optimal attraction force for smooth and uninterrupted travelling of the moving body can be realized.

TECHNICAL FIELD

The present invention relates to a wall surface attraction type movingapparatus applicable to the maintenance/inspection, etc. of a large ironstructure, and particularly relates to a wall surface attraction typemoving apparatus and a magnet drive method for a wall surface attractiontype moving apparatus which perform attraction to a wall surface duringmovement by applying the magnetic force of a permanent magnet to thewall surface made of a magnetic substance.

BACKGROUND ART

For a structure formed with a magnetic substance such as a large ironstructure, attraction to the structure can be performed by magneticforce. Therefore, for the maintenance/inspection of a structure such asthis, etc., there has been developed a wall surface attraction typemoving apparatus which can make a moving body attract to a structure bytaking advantage of magnetic force. In such a wall surface attractiontype moving apparatus, since a moving body is caused to be attracted toa structure by magnetic force, the travel of a moving body can also beperformed even if the surface of a structure on which the moving bodytravels is not vertically present downward, i.e., even against avertical surface.

For instance, FIG. 7 is a schematic constitution diagram showing aconventional wall surface attraction type moving apparatus, and as shownin FIG. 7, the moving apparatus is constituted by a moving body (movingcarriage) 110 travelable along the surface of a structure, and travelwheels 112 and 113, a magnetic force type attraction mechanism 130, anda manipulator 120 for operations such as maintenance/inspection,respectively installed in this moving carriage 110.

Particularly, the attraction mechanism 130 is provided with anadvancing/retreating rod 132 projected from the lower surface of themoving carriage 110, a permanent magnet (hereinafter referred to as amagnet) 134 installed on the point end of this advancing/retreating rod132, and a drive mechanism 131 or driving the magnet 134 to leave orapproach a magnetic travel surface (magnetic wall surface) 102 under themoving carriage 110 by advancing or retreating the advancing/retreatingrod 132.

And in order to adjust the distance between the magnet 134 and thetravel surface 102 and adjust the magnetic force (i.e., attractionforce) of the magnet 134 by controlling the drive mechanism 131, a forcesensor 133 and a controller (attraction force control section) 135 areprovided. The force sensor 133 is installed in the proximity of themagnet 134 and detects the strength of magnetic force which acts betweenthe magnet 134 and the travel surface 102. The attraction force controlsection 135 receives a detection signal corresponding to the magneticforce (i.e., attraction force) between the magnet 134 and the travelsurface 102 from this force sensor 133. This detection signal controlsthe drive mechanism 131 with feedback control based on the detectionsignal so that this magnetic force (attraction force) becomes apredetermined value, thereby adjusting the advancement/retreat quantityof the advancing/retreating rod 132 and adjusting the distance betweenthe magnet 134 and the travel surface 102.

In other words, the magnetic force (attraction force) acting between themagnet 134 and the travel surface 102 varies in correspondence to thedistance between the magnet 134 and the travel surface 102. Therefore,in order for a predetermined magnetic force to act between the magnet134 and the travel surface 102, the distance between the magnet 134 andthe travel surface 102 needs to be controlled in correspondence to thispredetermined magnetic force. The attraction force control section 135controls the distance between the magnet 134 and the travel surface 102through the drive mechanism 131 so that the magnetic force actingbetween the magnet 134 and the travel surface 102 becomes apredetermined magnitude, while the detection signal of the force sensor133 is being fed back.

With such control by the attraction force control section 135, forexample even if the travel surface 102 has irregularities thereon and isin a state like an uneven ground, the position of the magnet 134 will beadjusted in correspondence to this travel surface 102 and therefore theattraction force by the magnet 134 can be held nearly constant at alltimes. In other words, with such control, the gap between the magnet 134and the travel surface 102 to which this magnet 134 is opposed becomesconstant at all times and the required attraction force is stablyexhibited, whereby the attraction of the moving carriage 110 to thetravel surface 102 is performed with reliability.

Incidentally, in the case where a wall surface attraction type movingapparatus such as the above-mentioned rides across an obstacle on thetravel surface 102 such, for example, as a projection 102A shown in FIG.8 or level difference 102B shown in FIG. 109, there is a need to adjustthe advancement/retreat quantity of the advancing/retreating rod 132 sothat the magnet 134 is not interfered with by the obstacle.

However, as shown in FIGS. 8 and 9, in the case where the apparatusrides across the projection 102A, level difference 102B, or the like,the magnet 134 must be moved away from the opposite travel surface 102in correspondence to the height of the projection 102A, level difference102B, or the like. If done in this manner, the magnet force actingbetween the magnet 134 and the travel surface 102 will be considerablyreduced and therefore it will be difficult to ensure attraction forcenecessary to cause the moving carriage 110 to be attracted to the travelsurface 102 with reliability. Of course, if the magnet 134 is madepowerful, attraction force can be increased, but this is undesirablebecause, in order to ensure necessary attraction force, an extremelylarge magnet 134 is needed, a considerable increase in the weight orsize of the moving apparatus is incurred, an increase in the capacity ofa drive unit such as a motor associated with travel drive is required,and so on.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-mentionedproblems, and an object of the invention is to provide a wall surfaceattraction type moving apparatus and a magnet drive method for a wallsurface attraction type moving apparatus which can make the apparatus beattracted to a travel surface with reliability so that a permanentmagnet is not interfered with by an obstacle when riding across anobstacle on a wall surface (travel surface), while suppressing anincrease in the weight and size of the apparatus.

To this end, in a wall surface attraction type moving apparatus providedwith a moving body which moves on a wall surface made of a magneticsubstance, an attraction mechanism provided in the moving body, and acontroller for controlling the attraction mechanism, the wall surfaceattraction type moving apparatus of the present invention ischaracterized in that: said attraction mechanism is provided with apermanent magnet installed in the moving body, a drive mechanism foradvancing or retreating the permanent magnet in a direction which leavesor approaches the wall surface, and an attraction force sensor fordetecting an attraction force of the permanent magnet to the wallsurface; said attraction mechanism is provided with a plurality of setsof attraction mechanisms; and said controller controls the drivemechanisms in the attraction mechanisms on the basis of detectioninformation from said attraction force sensors so that the required wallsurface attraction force which can hold the moving body on the wallsurface is generated by the sum total of wall surface attraction forcesof the permanent magnets in the attraction mechanisms.

By constitution such as this, with the magnetic force acting between thepermanent magnets respectively provided in a plurality of attractionmechanisms and the wall surface made of a magnetic substance as wallsurface attraction force, the moving body moves on the wall surfacewhile being attracted to the wall surface. At this time, the attractionforces of the magnets to the wall surface are detected by the attractionforce sensors. The controller controls the drive mechanisms of theattraction mechanisms on the basis of detection information from theattraction force sensors so that the sum total of the wall surfaceattraction forces of the permanent magnets becomes the required wallsurface attraction force which can hold the moving body on the wallsurface.

Thus, the required wall surface attraction force is always ensured as awhole by cooperation of a plurality of attraction mechanisms. Therefore,even in the case where there is a possibility that the permanent magnetin any of the attraction mechanisms will be interfered with by theobstacle, the drive mechanism of this attraction mechanism is controlledso that the interference between the permanent magnet and the obstacleis avoided, whereby the required wall surface attraction force canalways be ensured as a whole through the other attraction mechanisms.This makes it possible to move the moving body on the wall surfacewithout hindrance while holding it onto the wall surface reliably.

In addition, since the sum total of the wall surface attraction forcesof the permanent magnets is controlled so as to become the required wallsurface attraction force, an excessive increase in the wall surfaceattraction force can also be avoided. For example, even in the casewhere the moving body rides across an obstacle such as level differenceor a projection, the load associated with movement is reduced and thereis also an effect that the moving function is enhanced.

Also, the above-mentioned attraction mechanism may be constituted bysaid permanent magnet, said drive mechanism, and said attraction forcesensor, and also by a position sensor for detecting aleaving/approaching direction position of the permanent magnet againstsaid wall surface, and an obstacle sensor for detecting an approach ofan obstacle present on the wall surface to the permanent magnet. On thebasis of detection information from said position sensors, attractionforce sensors, and obstacle sensors, said controller may be constitutedso as to control the drive mechanisms so that said required wall surfaceattraction force is generated by the sum total of wall surfaceattraction forces of the permanent magnets in the drive mechanisms, andso as to control the drive mechanism so that in the case where there isa possibility that the permanent magnet will be interfered with by theobstacle, this interference is avoided.

By constitution such as this, with the magnetic force acting between thepermanent magnets respectively provided in a plurality of attractionmechanisms and the wall surface made of a magnetic substance as wallsurface attraction force, the moving body moves on the wall surfacewhile being attracted to the wall surface. At this time, theleaving/approaching direction position of the permanent magnet againstthe wall surface is detected by the position sensor, and the attractionforce of the permanent magnet to the wall surface is detected by theattraction force sensor. The approach of the obstacle present on thewall surface to the permanent magnet is detected by the obstacle sensor.The controller controls the drive mechanisms of the attractionmechanisms on the basis of detection information from the positionsensor, attraction force sensor, and obstacle sensor so that the sumtotal of the wall surface attraction forces of the permanent magnetsbecomes the required wall surface attraction force which can hold themoving body on the wall surface.

And in the case where there is a possibility that the permanent magnetin any of the attraction mechanisms will be interfered with by theobstacle, the drive mechanism of this attraction mechanism iscontrolled, thereby avoiding the interference between the permanentmagnet and the obstacle. During this interference avoidance, althoughthe attraction force of the permanent magnet of the attraction mechanismwhich becomes an object of control will usually be weakened because thepermanent magnet is adjusted so as to be moved away from the wallsurface, the drive mechanism of the other attraction mechanism iscontrolled so that the sum total of the attraction forces of thepermanent magnets becomes the required wall surface attraction.Therefore, since the required surface wall attraction force is ensuredas a whole, the moving body is held with reliability on the wallsurface.

Therefore, the moving body can be held with reliability on the wallsurface and moved on the wall surface, while the interference betweenthe permanent magnet and the obstacle is being avoided with reliability.

In addition, by control such that the sum total of the wall surfaceattraction forces of the permanent magnets becomes the required wallsurface attraction force, an excessive increase in the wall surfaceattraction force due to interference avoidance can also be avoided.Therefore, for example, even in the case where the moving body ridesacross an obstacle such as level difference or a projection, the loadassociated with movement is reduced and there is also an effect that themoving function is enhanced.

Furthermore, the permanent magnets of said attraction mechanisms may bedisposed so that their positions are offset longitudinally in a movingdirection of said moving body. On the basis of detection informationfrom said obstacle sensors, with respect to one attraction mechanism ofsaid plurality of attraction mechanisms which has the possibility ofsaid permanent magnet being interfered with by said obstacle, saidcontroller may perform retreat adjustment of the permanent magnetagainst the wall surface through said drive mechanism so that thisinterference is avoided, and at the same time, with respect to oneattraction mechanism of said plurality of attraction mechanisms whichhas no possibility of the permanent magnet being interfered with by saidobstacle, said controller may perform advancement adjustment of thepermanent magnet against the wall surface through said drive mechanismso that said required wall surface attraction force is generated by thesum total of wall surface attraction forces of the permanent magnets insaid drive mechanisms.

By constitution such as this, in the case where there is a possibilitythat the permanent magnet in any of the attraction mechanisms will beinterfered with by the obstacle, retreat adjustment of the permanentmagnet against the wall surface is performed through the drive mechanismcontrolled by the controller, thereby avoiding such interference. Inthis retreat-adjusted permanent magnet, the wall surface attractionforce is reduced. However, at the same time as this interferenceavoidance control, the other attraction mechanism is present which hasno possibility of the permanent magnet being interfered with by theabove-mentioned obstacle, and with respect to this attraction mechanism,advancement adjustment of the permanent magnet against the wall surfaceis suitably performed and the sum total of the wall surface attractionforces of the permanent magnets in the drive mechanisms is controlled soas to reach the required wall surface attraction force, so the movingbody is held with reliability on the wall surface.

This makes it possible to hold the moving body on the wall surfacereliably and move it on the wall surface while the interference betweenthe permanent magnet and the obstacle is being avoided with reliability.Of course, as described above, an excessive increase in the wall surfaceattraction force can also be avoided, and there is also an effect thatthe moving function is enhanced.

Furthermore, the above-mentioned obstacle sensors may be constituted soas to detect said obstacle present on the wall surface by detecting adistance between said wall surface and an object in a detectiondirection oriented onto said wall surface just under said moving body.Also the obstacle sensors may be provided with front obstacle sensorsrespectively installed directly before said permanent magnets in saidmoving direction. If any of said plurality of front obstacle sensorsdetects the presence of said obstacle, on the basis of a distance to theobstacle detected with the front obstacle sensor and saidleaving/approaching direction position of a corresponding permanentmagnet detected with said position sensor, said controller may controladvancement or retreat adjustment of the permanent magnet through saiddrive mechanism.

By constitution such as this, it also becomes possible to perform theposition adjustment of the permanent magnet against the obstacle in ashort time and moreover efficiently.

Furthermore, in the case where any of said plurality of front obstaclesensors detects the presence of said obstacle and there is a possibilitythat the obstacle will be interfered with by a corresponding permanentmagnet, said controller may perform retreat adjustment of the permanentmagnet through said drive mechanism by a quantity that can avoid theinterference.

By constitution such as this, an advantage of being able to perform theinterference control of the obstacle of the permanent magnet in a shorttime and moreover efficiently and reliably is obtained.

In addition, it is preferable that the retreat adjustment quantity foravoiding the interference between said permanent magnet and the obstaclebe set so that said leaving/approaching direction position of thepermanent magnet detected with said position sensor becomes longer by apredetermined distance than a distance to said obstacle detected withsaid front obstacle sensor.

By constitution such as this, the interference control of the obstacleof the permanent magnet can be performed with reliability.

Furthermore, in the case where any of said plurality of front obstaclesensors detects the presence of said obstacle and the obstacle is agroove-shaped obstacle located away from a corresponding permanentmagnet, said controller may be constituted so as to ensure said requiredwall surface attraction force by performing advancement adjustment ofthe permanent magnet through said drive-mechanism.

By constitution such as this, it also becomes possible to perform theposition adjustment of the permanent magnet against the obstacle in ashort time and moreover efficiently.

Furthermore, the above-mentioned obstacle sensors may be constituted soas to detect said obstacle present on the wall surface by detecting adistance between said wall surface and an object in a detectiondirection oriented onto said wall surface just under said moving body.Also, the obstacle sensors may be provided with rear obstacle sensorsrespectively installed directly after said permanent magnets in saidmoving direction. If any of said plurality of rear obstacle sensorsdetects the presence of said obstacle during a retreat of said movingbody, on the basis of a distance to the obstacle detected with the rearobstacle sensor and said leaving/approaching direction position of acorresponding permanent magnet detected with said position sensor, saidcontroller may be constituted so as to perform advancement or retreatadjustment of the permanent magnet through said drive mechanism.

By constitution such as this, even if there is present an obstacle on aflat surface during a retreat of the moving body, it will be possible toperform the position adjustment of the permanent magnet against theobstacle in a short time and moreover efficiently.

Also, in a magnet drive method for a wall surface attraction type movingapparatus

which is provided with a moving body which moves on a wall surface madeof a magnetic substance and an attraction mechanism provided in themoving body,

in which said attraction mechanism is provided with a permanent magnetinstalled in said moving body and a drive mechanism for advancing orretreating the permanent magnet in a direction which leaves orapproaches said wall surface and also provided with a position sensorfor detecting a leaving/approaching direction position of the permanentmagnet against the wall surface, an attraction force sensor fordetecting an attraction force of the permanent magnet to the wallsurface, and an obstacle sensor for detecting an approach of an obstaclepresent on the wall surface to the permanent magnet, and lastly

in which said attraction mechanism is provided with a plurality of setsof attraction mechanisms,

the magnet drive method for a wall surface attraction type movingapparatus of the present invention is characterized by comprising thesteps of:

if an approach of said obstacle present on said wall surface to saidpermanent magnet is detected by any of said obstacle sensors;

setting an appropriate distance to the wall surface on this side of theobstacle of one permanent magnet of said permanent magnets whichapproaches the obstacle, in correspondence to a distance to saidobstacle detected with the obstacle sensor;

controlling the drive mechanism of the permanent magnet which approachessaid obstacle in correspondence to this set appropriate distance; and

controlling the drive mechanism of the other permanent magnet of thepermanent magnets so that said required wall surface attraction force isgenerated by the sum total of wall surface attraction forces of saidpermanent magnets.

By constitution such as this, in the case where there is a possibilitythat the permanent magnet in any of the attraction mechanisms will beinterfered with by the obstacle, the drive mechanism of this attractionmechanism is controlled, thereby avoiding the interference between thepermanent magnet and the obstacle. During this interference avoidance,although the attraction force of the permanent magnet of the attractionmechanism which becomes an object of control will usually be weakenedbecause the permanent magnet is adjusted so as to be moved away from thewall surface, the drive mechanism of the other attraction mechanism iscontrolled so that the sum total of the attraction forces of thepermanent magnets becomes the required wall surface attraction.Therefore, since the required surface wall attraction force is ensuredas a whole, the moving body is held with reliability on the wallsurface.

Therefore, the moving body can held with reliability on the wall surfaceand moved on the wall surface, while the interference between thepermanent magnet and the obstacle is being avoided with reliability.

In addition, by control such that the sum total of the wall surfaceattraction forces of the permanent magnets becomes the required wallsurface attraction force, an excessive increase in the wall surfaceattraction force due to interference avoidance can also be avoided.Therefore, for example, even in the case where the moving body ridesacross an obstacle such as level difference or a projection, the loadassociated with movement is reduced and there is also an effect that themoving function is enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing a wall surface attraction type movingapparatus as one embodiment of the present invention;

FIG. 2 is a plan view showing the wall surface attraction type movingapparatus as one embodiment of the present invention;

FIG. 3 is a front view showing the wall surface attraction type movingapparatus as one embodiment of the present invention;

FIGS. 4(A) trough 4(E) are all diagrams for describing the wall surfaceattraction type moving apparatus and a magnet drive method for a wallsurface attraction type moving apparatus as one embodiment of thepresent invention and are schematic views showing operation while ridingacross an obstacle (level difference), the operation having been shownin order of FIGS. 4(A) through 4(E);

FIGS. 5(A) trough 5(E) are all diagrams for describing the wall surfaceattraction type moving apparatus and the magnet drive method for a wallsurface attraction type moving apparatus as one embodiment of thepresent invention and are schematic views showing operation while ridingacross an obstacle (projection), the operation having been shown inorder of FIGS. 5(A) through 5(E);

FIG. 6 is a schematic view for describing the advantages of the wallsurface attraction type moving apparatus and the magnet drive method fora wall surface attraction type moving apparatus as one embodiment of thepresent invention;

FIG. 7 is a schematic side view showing a conventional wall surfaceattraction type moving apparatus;

FIG. 8 is a schematic view for describing problems associated with theconventional wall surface attraction type moving apparatus; and

FIG. 9 is a schematic view for describing problems associated with theconventional wall surface attraction type moving apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will hereinafter be described bythe drawings.

FIGS. 1 through 6 show a wall surface attraction type moving apparatusand a magnet drive method for a wall surface attraction type movingapparatus as one embodiment of the present invention.

As shown in FIGS. 1 through 3, the wall surface attraction type movingapparatus of the present invention is provided with a moving body (mainbody) 5 travelable along the surface (travel surface 30) of a structure,a pair of rear wheels 7a and 7b installed through drive mechanisms 8aand 8b respectively on the rear portion of the main body 5, and a frontwheel 9 installed through a drive mechanism 10 on the front portion ofthis main body 5. The main body 5 is equipped with a manipulator (notshown), etc. The rear wheels 7a and 7b and front wheel 9 are rotatablysupported by the drive mechanisms 8a, 8b, and 10, respectively. The rearwheels 7a and 7b and front wheel 9 are also driven to rotate by motors(not shown) incorporated in the drive mechanisms 8a, 8b, and 10,respectively, whereby the main body 5 is movable.

Among them, the drive mechanism 10 rotatably supporting the front wheel9, as shown in FIGS. 2 and 3, is fixed to a steering shaft 12, which isin turn supported on the main body 5 through a bearing 11. Also, theouter circumference of the steering shaft 12, as shown in FIG. 3, isprovided with a gear 13, which in turn meshes with a gear 15 through anidle gear 14 supported on the side of the main body 5 so that it is freeto rotate. The gear 15 is driven to rotate by a motor (not shown)incorporated in a steering drive mechanism 16. Therefore, with the drivemechanism 16, the steering shaft 12 is drive to rotate through the gears15, 14, and 13, whereby the front wheel 9 is steered.

And, as shown in FIG. 1, the main body 5 is further provided with aplurality (here, two) of attraction mechanisms 40a and 40b. Theattraction mechanisms 40a and 40b are provided with magnet drivemechanisms 1a and 1b installed in the main body 5 and magnets (permanentmagnets) 2a and 2b installed downward on the lower end portions of theshafts 4a and 4b of these magnet drive mechanisms 1a and 1b,respectively.

The shaft center lines of the shafts 4a and 4b of the magnet drivemechanisms 1a and 1b are both set in a direction perpendicular to thetravel surface (magnetic wall surface) 30. The attraction mechanisms 40aand 40b drive the shafts 4a and 4b of such magnet drive mechanisms 1aand 1b to advance or retreat in the direction perpendicular to thetravel surface 30, thereby adjusting the magnets 2a and 2b so that theyadvance or retreat in a direction which leaves or approaches the travelsurface 30.

Incidentally, the attraction mechanisms 40a and 40b are arranged on thefront portion (near the front wheel 9) of the main body and on the rearportion (near the rear wheels 7a and 7b) of the main body, respectively.Therefore, the magnets 2a and 2b provided in the attraction mechanisms40a and 40b are arranged so that their positions are offsetlongitudinally in the moving direction of the main body (moving body) 5.

In addition, the attraction mechanisms 40a and 40b are further providedwith position sensors 19a and 19b for respectively detecting theleaving/approaching direction positions of the magnets 2a and 2b againstthe travel surface 30, attraction force sensors (force sensors) 3a and3b for respectively detecting the attraction forces of the magnets 2aand 2b to the travel surface 30, and obstacle sensors 17a, 17b, 18a, and18b for detecting the approach of an obstacle such as level differenceor a protrusion present on the travel surface 30 to the magnets 2a and2b.

Among the sensors, the position sensors 19a and 19b are constituted bystroke sensors which detect the advancement/retreat strokes of themagnets 2a and 2b.

Also, the force sensors 3a and 3b consist, for example, of discsprovided with a strain gauge. The force sensors 3a and 3b are interposedbetween the point end portion of the shaft 4a and the magnet 2a andbetween the point end portion of the shaft 4b and the magnet 2b. Theforce sensors 3a and 3b detect the attraction forces (wall surfaceattraction forces) of the magnets 2a and 2b, by detecting strainscorresponding to forces with which the magnets 2a and 2b attempt to moveaway from the shafts 4a and 4b as magnetic forces (attraction forces)arising from the magnets 2a and 2b become great, conversely speaking, bydetecting strains corresponding to tension forces which are reducedbetween the magnet 2a and the shaft 4a and between the magnet 2b and theshaft 4b as magnetic forces (attraction forces) arising from the magnets2a and 2b become small. Therefore, for example in the case where strainscorresponding to forces with which the magnets 2a and 2b attempt to moveaway from the shafts 4a and 4b are measured, if the strain is great,attraction force (wall surface attraction force) will also be greater.

Also, the obstacle sensors 17a, 17b, 18a, and 18b can be classified intofront obstacle sensors 17a and 18a arranged directly before the magnets2a and 2b and rear obstacle sensors 17b and 18b arranged directly afterthe magnets 2a and 2b. And the obstacle sensors 17a, 17b, 18a, and 18bare all constituted by distance sensors for detecting a distance to amaterial body (object) which is present in a direction of detection. Thedetection directions of the sensors 17a, 17b, 18a, and 18b are set so asto go onto the travel surface 30 under the main body 5 (usually, in adirection perpendicular to the travel surface 3). Note that the rearobstacle sensor 17b associated with the front magnet 2a and the frontobstacle sensor 18a associated with the rear magnet 2b are located atapproximately the center of the main body 5 in the longitudinaldirection.

Therefore, in the case where the distance to an object detected with theobstacle sensors 17a, 17b, 18a, and 18b is a magnitude equivalent to thedistance to the travel surface 30, it can be judged that there is nosuch obstacle as level difference or a projection on the travel surface30. Also, in the case where the distance to an object detected issmaller than a magnitude equivalent to the distance to the travelsurface 30, it can be judged that there is an obstacle, such as up ordown level difference or a projection, on the travel surface 30. Inaddition, in the case where the distance to an object detected isgreater than a magnitude equivalent to the distance to the travelsurface 30, it can be judged that there is up or down level difference,a groove, or the like on the travel surface 30.

Such detection results by the position sensors 19a and 19b, forcesensors 3a and 3b, and obstacle sensors 17a, 17b, 18a, and 18b aretransmitted to a controller (transmitter) 20. Based on the detectioninformation by these position sensors 19a and 19b, force sensors 3a and3b, and obstacle sensors 17a, 17b, 18a, and 18b , the controller 20controls the magnet drive mechanisms 1a and 1b of the attractionmechanisms 40a and 40b individually.

Now, a description will be made of the control contents that areperformed by the controller 20 which is the characteristic part of thewall surface attraction type moving apparatus of the present invention.

In this controller 20, advancement or retreat adjustment of the magnets2a and 2b are performed through the magnet drive mechanisms 1a and 1b ofthe attraction mechanisms 40a and 40b in a direction which leaves orapproaches the travel surface 30 so that the sum total of the attractionforces (wall surface attraction forces) in the attraction mechanisms 40aand 40b, detected with the force sensors 3a and 3b, becomes the requiredwall surface attraction force at all times.

Note that the required wall surface attraction force is attraction forceby magnetic force produced between the travel surface 30 which is amagnetic wall surface and the magnets 2a and 2b, and is set as a forceof the magnitude which can reliably hold the wall surface attractiontype moving apparatus of the present invention onto the travel surface30.

Also, in the controller 20, if any of the obstacle sensors 17a, 17b,18a, and 18b detects the presence of an obstacle such as leveldifference or a projection, on the basis of the distance to the obstacledetected with the obstacle sensor detecting the presence of thisobstacle and position information from the position sensor 19a or 19b ofthe magnet 2a or 2b directly after the obstacle sensor detecting thisobstacle, retreat adjustment of the magnet 2a or 2b will be performedthrough the magnet drive mechanism 1a or 1b in a direction which leavesthe travel surface 30 so that the magnet 2a or 2b is not be interferedwith by this obstacle.

In addition, at the same time as this retreat adjustment, in thecontroller 20, since the wall surface attraction force of the magnet 2aor 2b subjected to the retreat adjustment is reduced, advancementadjustment of the other magnet, i.e., advancement adjustment of themagnet 2a or 2b not being interfered with by the obstacle is performedthrough the magnet drive mechanism 1a or 1b in a direction whichapproaches the travel surface 30, whereby the sum total of attractionforces (wall surface attraction forces) in the attraction mechanisms 40aand 40b is controlled so as to become the required wall surfaceattraction force at all times.

The wall surface attraction type moving apparatus as one embodiment ofthe present invention is constituted as described above. Therefore, bythe wall surface attraction forces which are exhibited through theattraction mechanisms 40a and 40b, even if the surface of a structure onwhich the apparatus travels is not vertically present downward, i.e.,for example even against a vertical surface, the movement of theapparatus can be performed.

And if a description will be made of the operation of the apparatus ofthe present invention (a magnet drive method for the wall surfaceattraction type moving apparatus according to this embodiment), in thecase where the apparatus of the present invention rides across anobstacle such as level difference or a projection, it will operate asfollows:

For instance, when the apparatus of the present invention moves(travels) on the travel surface (vertical surface) 30 oriented in avertical direction, in the case where it rides across level difference(up level difference) 31 present on the travel surface 30, as shown inFIGS. 4(A) through 4(E), the positions of the magnets 2a and 2b areadjusted by the controller 20.

In other words, first, as shown in FIG. 4(A), until the apparatusarrives near the level difference 31, the controller 20 adjusts thepositions of the magnets 2a and 2b through the magnet drive mechanisms1a and 1b of the attraction mechanisms 40a and 40b so that the magnets2a and 2b are located at a nearly equal distance h_(o) away from theflat travel surface 30, thereby controlling the sum total FS (=F₁ +F₂)of the attraction forces F₁ and F₂ of the attraction mechanisms 40a and40b so that it becomes the required wall surface attraction force F.

And if the apparatus arrives near the level difference 31, the frontwheel will first ride across this level difference 31. With advancementof the apparatus, if the front magnet 2a approaches this leveldifference 31, as shown in FIG. 4(B), the front obstacle sensor 17aarranged directly before the front magnet 2a will respond to this leveldifference 31.

In other words, since the distance to the side of the travel surface 30detected with the front obstacle sensor 17a becomes shorter thantheretofore, the controller 20 can judge that there is something(obstacle) at a closer distance than the travel surface 30.

At the same time as this judgment, the controller 20 computes the heightH of the obstacle (here, the level difference 31) from the distance tothe obstacle detected with this front obstacle sensor 17a, and alsocompares the current position of the magnet 2a (distance h_(o) with thetravel surface 30) detected by the position sensor 19a with the distance(=H+δh) of excess clearance length δh added to the height H of thisobstacle (level difference 31). This distance (=H+δh) is equivalent toan appropriate distance from the travel surface (wall surface) 30 of themagnet on this side of the obstacle.

And if the current position of the magnet 2a (distance h_(o) with thetravel surface 30) is shorter than the appropriate distance (H+δh), thecontroller 20 will perform retreat adjustment of the front magnet 2athrough the magnet drive mechanism 1a so that the position of the magnet2a is away from the travel surface 30 by the appropriate distance(H+δh).

With this retreat adjustment of magnet 2a, the attraction force of theattraction mechanism 40a is reduced. Therefore, the controller 20, alongwith this retreat adjustment of magnet 2a, performs advancementadjustment of the magnet 2b by this amount of reduction α in theattraction force of the attraction mechanism 40a, thereby increasing theattraction force of the attraction mechanism 40b. With this, theattraction force of the attraction mechanism 40a becomes from F₁ to (F₁-α), and the attraction force of the attraction mechanism 40b becomesfrom F₂ to (F₂ +α). Therefore, the total attraction force FS of bothattraction mechanisms 40a and 40b still holds a constant value (requiredwall surface attraction force F=F₁ +F₂) like the following equation.

    FS=(F.sub.1 -α)+(F.sub.2 +α)=F.sub.1 +F.sub.2

And if the apparatus advances further, then the front magnet 2a ridesacross this level difference 31 and arrives onto a travel surface 32 onthe high step side, and then the front magnet 2a comes to generatemagnetic force (attraction force) between it and the travel surface 32on the high step side, the attraction force at the front magnet 2a willbe great. Therefore, as shown in FIG. 4(C), the controller 20 adjuststhe positions of the magnets 2a and 2b through the magnet drivemechanisms 1a and 1b of the attraction mechanisms 40a and 40b so thatthe magnets 2a and 2b are again located at a nearly equal distance h_(o)away from the travel surfaces 30 and 32. With this adjustment, if theattraction forces of the attraction mechanisms 40a and 40b are taken tobe F₁ and F₂, the sum total FS (=F₁ +F₂) of these attraction forces F₁and F₂ are controlled so as to become the required wall surfaceattraction force F.

And if the apparatus advances further and the rear magnet 2b approachesthis level difference 31, as shown in FIG. 4(D), the front obstaclesensor 18a arranged directly before the rear magnet 2b will respond tothis level difference 31.

In other words, since the distance to the side of the travel surface 30detected with the front obstacle sensor 18a becomes shorter thantheretofore, the controller 20 can judge that the rear magnet 2b hasapproached the level difference 31.

At the same time as this judgment, the controller 20 computes the heightH of the obstacle (here, the level difference 31) from the distance tothe obstacle detected with this rear obstacle sensor 18a, and alsocompares the current position of the magnet 2b (distance h_(o) with thetravel surface 30) detected by the position sensor 19b with theappropriate distance (=H+δh) of excess clearance length δh added to theheight H of this level difference 31. If the current position of themagnet 2b (distance h_(o) with the travel surface 30) is shorter thanthe appropriate distance (H+δh), the controller 20 will perform retreatadjustment of the rear magnet 2b through the magnet drive mechanism 1bso that the position of the magnet 2b is away from the travel surface 30by the appropriate distance (H+δh).

With this retreat adjustment of magnet 2b, the attraction force of theattraction mechanism 40b is reduced. Therefore, the controller 20, alongwith this retreat adjustment of magnet 2b, performs advancementadjustment of the magnet 2a, thereby increasing the attraction force ofthe attraction mechanism 40b by this amount of reduction α in theattraction force of the attraction mechanism 40a. With this, theattraction force of the attraction mechanism 40a becomes from F₁ to (F₁+α), and the attraction force of the attraction mechanism 40b becomesfrom F₂ to (F₂ -α). Therefore, the total attraction force FS of bothattraction mechanisms 40a and 40b still holds a constant value (requiredwall surface attraction force F=F₁ +F₂) like the following equation.

    FS=(F.sub.1 +α)+(F.sub.2 -α)=F.sub.1 +F.sub.2

And if the apparatus advances further, then the rear magnet 2b ridesacross this level difference 31 and arrives onto the travel surface 32on the high step side, and then the rear magnet 2b comes to generatemagnetic force (attraction force) between it and the travel surface 32on the high step side, the attraction force at the rear magnet 2b willbe great. Therefore, as shown in FIG. 4(E), the controller 20 adjuststhe positions of the magnets 2a and 2b through the magnet drivemechanisms 1a and 1b of the attraction mechanisms 40a and 40b so thatthe magnets 2a and 2b are again located at a nearly equal distance h_(o)away from the travel surfaces 30 and 32. With this adjustment, if theattraction forces of the attraction mechanisms 40a and 40b are taken tobe F₁ and F₂, the sum total FS (=F₁ +F₂) of these attraction forces F₁and F₂ are controlled so as to become the required wall surfaceattraction force F.

In this manner, if the sum total FS of the attraction forces of theattraction mechanisms 40a and 40b is controlled so as to become therequired wall surface attraction force F (=F₁ +F₂) at all times, theapparatus can ride across the level difference 31 without incurring theinterference between the magnets 2a and 2b and the level difference,while being brought into contact with the travel surfaces 30 to 32 withreliability. This makes a contribution to an enhancement in the mobilityof the wall surface attraction type moving apparatus.

Also, in the case where the apparatus rides across down level differencepresent on the travel surface 30, although not shown, the distance tothe side of the travel surface 30 detected by the front obstacle sensors17a and 18b becomes longer than heretofore, so the controller 20 canjudge that the magnet 2a and 2b have approached the down leveldifference. Even in this case, as with the case of the above-mentionedup level difference, if the sum total FS of the attraction forces of theattraction mechanisms 40a and 40b is controlled so as to become therequired wall surface attraction force F (=F₁ +F₂) at all times, theapparatus can ride across the down level difference without incurringthe interference between the magnets 2a and 2b and the level difference,while being brought into contact with the travel surfaces 30 to 32 withreliability.

On the other hand, for example when the apparatus of the presentinvention moves (travels) on the travel surface (vertical surface) 30oriented in a vertical direction, in the case where it rides across aprojection 33 present on the travel surface 30, as shown in FIGS. 5(A)through 5(E), the positions of the magnets 2a and 2b are adjusted by thecontroller 20.

In other words, the apparatus arrives near the projection 33, the frontwheel rides across the projection 33, and if the front magnet 2aapproaches this projection 33, as shown in FIG. 5(A), the front obstaclesensor 17a arranged directly before the front magnet 2a will firstrespond to this level difference 33.

In other words, since the distance to the side of the travel surface 30detected with the front obstacle sensor 17a becomes shorter thantheretofore, the controller 20 can judge that there is something(obstacle) at a closer distance than the travel surface 30.

At the same time as this judgment, the controller 20 computes the heightH of the obstacle (here, the projection 33) from the distance to theobstacle detected with this front obstacle sensor 17a, and also comparesthe current position of the magnet 2a (distance h_(o) with the travelsurface 30) detected by the position sensor 19a with the appropriatedistance (=H+δh) of excess clearance length δh added to the height H ofthis obstacle (projection 33).

And if the current position of the magnet 2a (distance h_(o) with thetravel surface 30) is shorter than the appropriate distance (H+δh), thecontroller 20 will perform retreat adjustment of the front magnet 2athrough the magnet drive mechanism 1a so that the position of the magnet2a is away from the travel surface 30 by the appropriate distance(H+δh).

With this retreat adjustment of magnet 2a, the attraction force of theattraction mechanism 40a is reduced. Therefore, the controller 20, alongwith this retreat adjustment of magnet 2a, performs advancementadjustment of the magnet 2b, thereby increasing the attraction force ofthe attraction mechanism 40b by this amount of reduction α in theattraction force of the attraction mechanism 40a. With this, theattraction force of the attraction mechanism 40a becomes from F₁ to (F₁-α), and the attraction force of the attraction mechanism 40b becomesfrom F₂ to (F₂ +α). Therefore, the total attraction force FS of bothattraction mechanisms 40a and 40b still holds a constant value (requiredwall surface attraction force F=F₁ +F₂) like the following equation.

    FS=(F.sub.1 -α)+(F.sub.2 +α)=F.sub.1 +F.sub.2

And the apparatus advances further, and as shown in FIG. 5(B), if thefront magnet 2a is located above this projection 33 and comes togenerate magnetic force (attraction force) between it and thisprojection 33, this time the attraction force at the front magnet 2awill be great, but, in the case where the area of the projection 33 issmall, sufficient attraction force (e.g., F₁) will not be obtained evenif the magnet 2a is close to the projection 33. For example, if theattraction force which is insufficient is taken to be β, all attractionforce that is obtained is only (F₁ -β).

Hence, in order to supplement this insufficiency by the rear attractionmechanism 40b, the controller 20 performs advancement adjustment of themagnet 2b, thereby increasing the attraction force of the attractionmechanism 40b by this amount of reduction β in the attraction force ofthe attraction mechanism 40a. With this, the attraction force of theattraction mechanism 40a becomes (F₁ -β), while the attraction force ofthe attraction mechanism 40b becomes (F₂ +β). Therefore, the totalattraction force FS of both attraction mechanisms 40a and 40b stillholds a constant value (required wall surface attraction force F=F₁ +F₂)like the following equation.

    FS=(F.sub.1 -β)+(F.sub.2 +β)=F.sub.1 +F.sub.2

And if the apparatus advances further and the rear magnet 2b approachesthis projection 33, as shown in FIG. 5(C), the front obstacle sensor 18aarranged directly before the rear magnet 2b will respond to thisprojection 33.

In other words, since the distance to the side of the travel surface 30detected with the front obstacle sensor 18a becomes shorter thantheretofore, the controller 20 can judge that the rear magnet 2b hasapproached the projection 33.

At the same time as this judgment, the controller 20 computes the heightH of the obstacle (here, the projection 33) from the distance to theobstacle detected with this rear obstacle sensor 18a, and also comparesthe current position of the magnet 2b (distance h_(o) with the travelsurface 30) detected by the position sensor 19b with the appropriatedistance (=H+δh) of excess clearance length δh added to the height H ofthis projection 33. If the current position of the magnet 2b (distanceh_(o) with the travel surface 30) is shorter than the appropriatedistance (H+δh), the controller 20 will perform retreat adjustment ofthe front magnet 2b through the magnet drive mechanism 1b so that theposition of the magnet 2b is away from the travel surface 30 by theappropriate distance (H+δh).

With this retreat adjustment of magnet 2b, the attraction force of theattraction mechanism 40b is reduced. Therefore, the controller 20, alongwith this retreat adjustment of magnet 2b, performs advancementadjustment of the magnet 2a, thereby increasing the attraction force ofthe attraction mechanism 40a by this amount of reduction α in theattraction force of the attraction mechanism 40b. With this, theattraction force of the attraction mechanism 40a becomes from F₁ to (F₁+α), and the attraction force of the attraction mechanism 40b becomesfrom F₂ to (F₂ -α). Therefore, the total attraction force FS of bothattraction mechanisms 40a and 40b still holds a constant value (requiredwall surface attraction force F=F₁ +F₂) like the following equation.

    FS=(F.sub.1 +α)+(F.sub.2 -α)=F.sub.1 +F.sub.2

And the apparatus advances further, and as shown in FIG. 5(D), if therear magnet 2b is located above this projection 33 and comes to generatemagnetic force (attraction force) between it and this projection 33, theattraction force at the rear magnet 2b will be great, but, in the casewhere the area of the projection 33 is small, sufficient attractionforce (e.g., F₂) will not be obtained even if the magnet 2b is close tothe projection 33. For example, if the attraction force which isinsufficient is taken to be β, all attraction force that is obtained isonly (F₂ -β).

Hence, in order to supplement this insufficiency by the front attractionmechanism 40a, the controller 20 performs advancement adjustment of themagnet 2a, thereby increasing the attraction force of the attractionmechanism 40a by this amount of reduction β in the attraction force ofthe attraction mechanism 40b. With this, the attraction force of theattraction mechanism 40b becomes (F₂ -β), while the attraction force ofthe attraction mechanism 40a becomes (F₁ +β). Therefore, the totalattraction force FS of both attraction mechanisms 40a and 40b stillholds a constant value (required wall surface attraction force F=F₁ +F₂)like the following equation.

    FS=(F.sub.1 +β)+(F.sub.2 -β)=F.sub.1 +F.sub.2

If the rear magnet 2b rides across this projection 33, it will generatemagnetic force (attraction force) between it and the travel surface 32and the attraction force at the rear magnet 2b will be great. Therefore,as shown in FIG. 5(E), the controller 20 adjusts the positions of themagnets 2a and 2b through the magnet drive mechanisms 1a and 1b of theattraction mechanisms 40a and 40b so that the magnets 2a and 2b areagain located at a nearly equal distance h_(o) away from the travelsurface 30. With this adjustment, the sum total FS of the attractionforces of the attraction mechanisms 40a and 40b are controlled so as tobecome the required wall surface attraction force F (=F₁ +F₂).

In this manner, if the sum total FS of the attraction forces of theattraction mechanisms 40a and 40b is controlled so as to become therequired wall surface attraction force F (=F₁ +F₂) at all times, theapparatus can ride across the projection 33 without incurring theinterference between the magnets 2a and 2b and the projection 33, whilebeing brought into contact with the travel surface 30 with reliability.This makes a contribution to an enhancement in the mobility of the wallsurface attraction type moving apparatus.

Also, in the case where the apparatus rides across a downward groovepresent in the travel surface 30, although not shown, the distance tothe side of the travel surface 30 detected by the front obstacle sensors17a and 18a becomes longer than heretofore, so the controller 20 canjudge that the magnet 2a and 2b have approached the groove. Even in thiscase, as with the case of the above-mentioned projection, if the sumtotal FS of the attraction forces of the attraction mechanisms 40a and40b is controlled so as to become the required wall surface attractionforce F (=F₁ +F₂) at all times, the apparatus can pass across a groovewithout producing excessive wall surface attraction force, while beingbrought into contact with the travel surface 30 with reliability.

In other words, if the attraction mechanism 40a or 40b is located abovea groove, the attraction force F₁ or F₂ will be reduced. In connectionwith this, for example if the attraction mechanism 40a or 40b locatedabove the groove is advanced downward to avoid a reduction in theattraction force F₁ or F₂, if only the other attraction mechanism 40b or40a not located above the groove is advanced downward, or if theattraction mechanism 40a or 40b located above the groove and the otherattraction mechanism 40b or 40a not located above the groove are bothadvanced downward, the sum total FS of the attraction forces can be madeto always become the required wall surface attraction force F (=F₁ +F₂)which is not excessive.

Also, in the case where the wall surface attraction type movingapparatus of the present invention retreats, on the basis of detectioninformation from the rear obstacle sensors 17b and 18b instead of thefront obstacle sensors 17a and 18a, if the attraction mechanism 40a or40b is controlled in a similar manner as the above-mentioned, theapparatus can ride across or pass across an obstacle without incurringthe interference between the magnets 2a and 2b and the obstacle.

Incidentally, in such a manner, when the apparatus rides across anobstacle such as the level difference 31 or the projection 33, the sumtotal FS of the attraction forces of the attraction mechanisms 40a and40b becomes the required wall surface attraction force F (=F₁ +F₂) atall times, so there is no possibility that the wall surface attractionforce will be excessive, and in this respect, the present invention alsomakes a contribution to an enhancement in the mobility of the apparatus.

In other words, for example, as shown in FIG. 6, if the load applied tothe wheel is taken to be W, the force (drive force) which pushes thewheel to be Q, the wheel diameter of the front wheel 9 or the rearwheels 7a and 7b to be D, the height of the level difference 31 to be s,the angle of the level difference 31 at which the wheel in contact withthe level difference 31 attempts to ride across the level difference 31to be θ, and the horizontal distance between the contact center line ofthe wheel and the contact point with the level difference 31 to be L, itwill be possible to ride across the level difference 31 if the followingequation is met. ##EQU1##

In the apparatus of the present invention, since the wall surfaceattraction force F does not become excessive, the load W in the aboveequation can be reduced, and if the load W becomes small, θ can beincreased. Furthermore, in other words, since the height s of the leveldifference 31 cross which the apparatus can ride can be made high, thepresent invention makes a contribution to an enhancement in the mobilityof the apparatus.

Note that the present invention is not to be limited to theabove-mentioned embodiments, but various modifications can be carriedout without departing from the gist of the invention.

For instance, while the embodiment of the present invention has beenprovided with two sets of front and rear attraction mechanisms, theinvention is not limited to the two sets, but three or more sets ofattraction mechanisms may be installed. Even in this case, any one ofthe attraction mechanisms is installed in front of or in the rear of theother attraction mechanism, and the permanent magnets of the attractionmechanisms are arranged so that the positions thereof are offsetlongitudinally in the moving direction of the above-mentioned movingbody. With this arrangement, even if any of the permanent magnetsretreats to avoid interference between it and an obstacle such as leveldifference or a projection, among the other permanent magnets there willalways be a permanent magnet which is not interfered with by theobstacle such as level difference or a projection. If advancementadjustment of this permanent magnet is performed, it will be possible tocontrol the total attraction force so that it becomes the required wallsurface attraction force F at all times, and therefore effects such asthe aforementioned can be obtained with reliability.

Also, in the embodiment of the present invention, although theadvancement/retreat position control of the magnets (permanent magnets)has been performed based on detection information from three kinds ofsensors, a position sensor, an attraction force sensor (force sensor),and an obstacle sensor, it is also considered that among these threekinds of sensors, some are equipped to perform the advancement/retreatposition control of the magnets (permanent magnets).

In other words, since the attraction force detected with the attractionforce sensor corresponds to the distance between the magnet and themagnetic wall surface (including an obstacle), it is also possible tocompute the distance between the magnet and the magnetic wall surface(including an obstacle) from the detection information of thisattraction force sensor. That is, it is also possible to use theattraction force sensor as a position sensor.

In addition, when the moving apparatus of the present invention ridesacross an obstacle on a wall surface such as level difference or aprojection, the detection information of the attraction force sensorchanges suddenly, so it is also possible to detect that there is presentan obstacle, such as level difference or a projection, which has apossibility of interfering with the permanent magnet. That is, it isalso possible to use the attraction force sensor as an obstacle sensor.

Therefore, it is considered that performing the advancement/retreatposition control of the permanent magnet on the basis of only thedetection information of the attraction sensor is also possible. Ofcourse, the attraction force sensor can predict the presence of anobstacle, but it is difficult to previously detect with reliability thedistance between the permanent magnet and an obstacle before thepermanent magnet is interfered with by the obstacle, as does theobstacle sensor. Therefore, position control of the permanent magnetwhich is good in precision, such as that in the embodiment of thepresent invention, is difficult. For more proper control, it ispreferable to provide a position sensor and an obstacle sensor as wellas an attraction force sensor and perform the position control of apermanent magnet on the basis of each detection information of thesesensors.

INDUSTRIAL APPLICABILITY

Even if an obstacle, etc., are present on a wall surface (travelsurface), the wall surface attraction type moving apparatus of thepresent invention can travel so that a permanent magnet is notinterfered with by this obstacle, while the apparatus is always beingbrought into contact with the wall surface with reliability by therequired wall surface attraction force F. Therefore, the presentinvention can enhance the mobility of the apparatus. Moreover, since thewall surface attraction force F does not become excessive, the apparatuscan be made so as to ride across higher level difference. In thisrespect, the mobility of the apparatus can also be enhanced. Therefore,if the apparatus of the present invention is employed in themaintenance/inspection, etc. of a structure formed with a magneticsubstance such as a large iron structure, the maintenance/inspection,etc., can be performed easily and quickly, and therefore the presentinvention is extremely useful.

We claim:
 1. A wall surface attraction type moving apparatuscomprising:moving body which moves on a wall surface made of a magneticsubstance; wheels which are supported by said moving body and includinga front wheel and a rear wheel; a plurality of attraction mechanismswhich are carried by the moving body; and a controller for controllingthe attraction mechanism; each of said attraction mechanisms including apermanent magnet carried by the moving body, and spaced from said wallsurface, a drive mechanism for advancing the permanent magnet toward orretracting the permanent magnet away from the wall surface, and anattraction force sensor for detecting an attraction force of thepermanent magnet acting on the wall surface; said permanent magnetsbeing longitudinally spaced from each other with respect to the runningdirection of said moving body; said controller being operable to controlthe drive mechanisms in the attraction mechanisms to obtain an optimalwall surface attraction force which attracts the moving body toward thewall surface by the total sum of wall surface attraction forces of thepermanent magnets in the attraction mechanisms in accordance with thedetection information from said attraction force sensors.
 2. The wallsurface attraction type moving apparatus as set forth in claim 1,whereinsaid attraction mechanisms include said permanent magnet, said drivemechanism, said attraction force sensor, a position sensor for detectinga facewise position of the individual permanent magnet with respect tosaid wall surface, and an obstacle sensor for detecting an obstacle;appearing in or approaching the travelling path of the apparatus, andwherein said controller controls the drive mechanisms to obtain saidoptimal wall surface attraction force by the total sum of wall surfaceattraction forces of the permanent magnets of the drive mechanisms inaccordance with the detection information from said position sensors,attraction force sensors, and obstacle sensors, and also controls thedrive mechanisms to prevent the individual permanent magnet from bumpingagainst the obstacle when the permanent magnet is likely to bump againstthe obstacle.
 3. The wall surface attraction type moving apparatus asset forth in claim 2, wherein:with respect to one of said plurality ofattraction mechanisms having the permanent magnet which is likely tobump against the obstacle, said controller retracts the last-namedpermanent magnet away from the wall surface by the action of said drivemechanism to avoid the obstacle based on the detection information fromsaid obstacle sensors, and at the same time, with respect to any otherof said plurality of attraction mechanisms having the permanent magnetwhich is unlikely to bump against the obstacle, said controller advancesthe permanent magnet toward the wall surface by the action of said drivemechanism to increase the wall surface attraction force of the otherpermanent magnet to an optimal value to supplement such reducedattraction forces of the retracted permanent magnet.
 4. The wall surfaceattraction type moving apparatus as set forth in claim 3,wherein saidobstacle sensors detect the obstacle appearing in the travelling path ofthe apparatus by detecting a distance between said wall surface and theobstacle appearing on said wall surface under said moving body; whereinsaid obstacle sensors include front obstacle sensors respectivelydisposed immediately ahead of said permanent magnets with respect tosaid moving direction of the moving body; and wherein if any of saidplurality of front obstacle sensors has detected said obstacle, saidcontroller advances the permanent magnet toward or retracts thepermanent magnet away from said wall surface by the action of said drivemechanism based on the distance between the permanent magnet whichcorresponds to said front obstacle sensor and the obstacle with respectto the running direction of said moving body detected by the frontobstacle sensor and based on said facewise position of the permanentmagnet detected by said position sensor.
 5. The wall surface attractiontype moving apparatus as set forth in claim 4, wherein if any of saidplurality of front obstacle sensors has detected the obstacle and whenthe permanent magnet which corresponds to said front obstacle sensor islikely to bump against the obstacle, said controller retracts thepermanent magnet away from said wall surface by the action of said drivemechanism by an appropriate extent to avoid the obstacle.
 6. The wallsurface attraction type moving apparatus as set forth in claim 5,wherein the appropriate extent of retraction of said permanent magnetfrom said wall surface to prevent said permanent magnet from bumpingagainst said obstacle is set so that said facewise position of thepermanent magnet as a result of detection of said position sensor isgreater by a predetermined distance than the distance between thepermanent magnet which corresponds to said front obstacle sensor and theobstacle detected by said front obstacle sensor.
 7. The wall surfaceattraction type moving apparatus as set forth in claim 4, wherein if anyof said plurality of front obstacle sensors has detected the obstaclewhich is in the form a groove-shaped obstacle located away from thepermanent magnet which corresponds to said front obstacle sensor, saidcontroller obtains said optimal wall surface attraction force byadvancing the permanent magnet toward said wall surface by the action ofsaid drive mechanism.
 8. The wall surface attraction type movingapparatus as set forth in claim 4,wherein said obstacle sensors detectthe obstacle appearing on the wall surface by detecting a distancebetween said obstacle sensors and the obstacle appearing on said wallsurface under said moving body, wherein said obstacle sensors includerear obstacle sensors respectively disposed immediately behind saidpermanent magnets with respect to said running direction of said movingbody, and wherein if any of said plurality of rear obstacle sensors hasdetected the obstacle during the retreating of said moving body, saidcontroller advances the permanent magnet toward or retracts thepermanent magnet away from said wall surface by the action of said drivemechanism based on the distance between the rear obstacle sensor and theobstacle detected by the rear obstacle sensor and based on said facewiseposition of the permanent magnet which corresponds to said rear obstaclesensor detected by said position sensor.
 9. A magnet drive method for awall surface attraction type moving apparatus comprising:a moving bodywhich moves on a wall surface made of a magnetic substance; wheelssupported by said moving body and including a front wheel and a rearwheel; and a plurality of attraction mechanisms carried by the movingbody each of the attraction mechanisms having a permanent magnet whichis carried by the moving body and is spaced from the wall surface, adrive mechanism for advancing the permanent magnet toward or retractingthe permanent magnet away from the wall surface, a position sensor fordetecting a facewise position of the permanent magnet with respect tothe wall surface, an attraction force sensor for detecting an attractionforce of the permanent magnet acting on the wall surface, an obstaclesensor for detecting an obstacle appearing on the wall surface andapproaching the permanent magnet, the permanent magnets beinglongitudinally spaced from each other with respect to the runningdirection of the moving body, said method comprising the following stepsof: if any of the obstacle sensors detects the obstacle appearing on thewall surface and approaches the permanent magnet, setting a prospectiveincreased distance (H+δh) between the wall surface and one of thepermanent magnets which approaches the obstacle base on a distancebetween the permanent magnet and the obstacle detected by the obstaclesensor; controlling the drive mechanism of one of the permanent magnetswhich approaches the obstacle in accordance with the set prospectiveincreased distance; and controlling the drive mechanism of the otherpermanent magnet to increase the wall surface attraction force of theother permanent magnet to an optimal value to supplement such reducedattraction force of the retracted permanent magnet.